I've got a pair of Sennheiser HD555 headphones and I'm trying to wire on a 3.5mm connector to the end, and there are 4 wires in the cable. Black, White, Red, Blue. Which ones to I connect to the tip, ring, and sleeve of the connector? I can't really find much around the internet, but I'm probably not looking in the right spot. All I can find is explanations of what T.R.S. are/is.

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Welcome to Audio.SE :) I presume you pulled off the previous plug to wire this new one in; what were they attached to on the old one?
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Warrior BobFeb 5 '11 at 2:39

its one of the ones thats molded on. I tried to cut it away, but couldn't get very far. I think I might have found it though.
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user473Feb 5 '11 at 2:43

If you do figure it out on your own please post your findings as an answer below for the benefit of others searching for the same thing.
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BenVFeb 5 '11 at 3:00

Tried to look for that exact model and NADA (there's a hd558 etc) but I did find it on google (bit weird...). From what I can see it's a "surround" headphone now I'm not sure of something: was the original trs 1/8" 4 pin one or is the surround driver just a simple ABR design?
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jlebreFeb 5 '11 at 11:00

3 Answers
3

If you still have the original 1/8" TRS with a bit of wire coming out, you can test with a multimeter or any other tool with a continuity test of some sort which wire goes to which pin. I am guessing that 2 of them will go to the shield or 1 not even connected at all

Is there a sure way to get the phase correct via this method? If so, I'd be delighted to learn how! Please let us know.
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d-_-bFeb 10 '11 at 2:54

Not sure if I made myself clear, but you will be testing the cable on the remainder of the plug that @Patick cut out. As said on the awesome @Brad post below, you'll get 2 of those guys going to the ground, one to the tip (left) on to the ring (right). You would only have a phase problem inverting the shield with the tip or ring. Now, sometimes they have a common earth, or 2 separate earths. Which means that it might be that 1 of the cables is actually not used, or that 2 of those will be wired to the sleeve!
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jlebreFeb 10 '11 at 21:34

I'm not sure if you can find this where you are, but I have this nifty little cable with a 3.5mm on one side and aligator clips on the other side. It's a nice thing for any technicians to have and will help solve your question.

Nothing. The aligator clips are even more simple. You could use a multimeter too I guess. Sometimes it's not clear from the impedance which wire goes to which head/earphone. Though, if you could open the entire set up, you could test just the wire rather than through the speaker, but then again, you could probably see the colors by then as well.
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d-_-bFeb 6 '11 at 1:15

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@jlebre: The multimeter will help you figure out which cables go together, but it won't help you figure out which cables are left and which right, and which phase is which. For that you need to try, and alligator clips will help you. But, making such a alligator squid is hardly worth it for just one headphone.
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Lennart RegebroFeb 7 '11 at 18:44

hmm just saying because my £20 multimeter came with aligator clips. Maybe if @Patick still have the bare wire on the original plug you could quickly test which cable goes to which pin, either by using resistance metering or continuity test
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jlebreFeb 7 '11 at 18:48

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@jlebre: Thats probably the best idea so far. You should make that an answer.
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Lennart RegebroFeb 9 '11 at 16:04

Take your multimeter, put it on the resistance setting, and figure out what is connected to what. Put one lead on one wire, and one on the other wire. You are looking for something that will measure somewhere between 8 and 120 ohms or so. Basically, anything that is not 0 ohms, and not completely open.

Chances are your white and black wires will be the speaker on one side, and the red and blue will be the speaker on the other. From there, it is likely that the black and blue wires are ground, and the red and white are hot.

Connect the tip to the L+, the ring to the R+, and both grounds to the sleeve.

The only thing wrong is that if this is wrong, you may either invert the polarity, or the L/R. Neither will break anything, but if one ear is of one polarity, and the other is of the other, it may sound interesting. That's why it is best to reference the original plug, if you still have it.